SPATIAL AND TEMPORAL ANALYSIS OF ANNUAL RAINFALL VARIATIONS IN TURKEY

This paper presents the spatial and temporal characteristics of Turkey 's annual rainfall data in the context of climatic variability. Basic data consists of the monthly rainfall totals from 91 stations with a r ecord length ranging from 54 to 64 years, during the period 1930-1993. Basic elements of the rainfall climatology have been examined and the n normalized rainfall anomaly series have been analysed for long-term trend and fluctuation and changes in runs of dry and wet years, for al l of Turkey, rainfall regime regions, and individual stations. All reg ional mean rainfall anomalies have tended to vary in a statistically c oherent manner over the rainfall regions. Area-averaged annual rainfal l series have decreased slightly over all of Turkey and apparently ove r the Black Sea and Mediterranean rainfall regions. Results of the Man n-Kendall test, however, have indicated that none of the decreasing tr ends in the area-averaged rainfall series were significant. Annual ser ies of 17 stations showed a significant trend in the mean and a majori ty of these trends are downward. Many of the stations have experienced marked low-frequency fluctuations in the annual rainfall. The concurr ences of the dry conditions between the rainfall regions and the rest of Turkey have appeared generally during the early 1930s, the late 195 0s, the early 1970s, around the 1980s and the early 1990s and of wet c onditions generally during the period 1935-1945, around the 1960s and the late 1970s. The change points for the beginning of drier than norm al conditions occurred in the early 1970s and early 1980s over most of the country. Annual rainfall variations over the rainfall regions exc ept the Black Sea region were related closely to those of the rest of Turkey.